/*
 * $Header: /cvsroot/mvnforum/myvietnam/src/net/myvietnam/mvncore/util/TimerUtil.java,v 1.10 2005/01/18 12:16:46 minhnn Exp $
 * $Author: minhnn $
 * $Revision: 1.10 $
 * $Date: 2005/01/18 12:16:46 $
 *
 * ====================================================================
 *
 * Copyright (C) 2002-2005 by MyVietnam.net
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * All copyright notices regarding MyVietnam and MyVietnam CoreLib
 * MUST remain intact in the scripts and source code.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Correspondence and Marketing Questions can be sent to:
 * info@MyVietnam.net
 *
 * @author: Minh Nguyen  minhnn@MyVietnam.net
 * @author: Mai  Nguyen  mai.nh@MyVietnam.net
 */
package com.hnedu.util;

import java.util.Timer;
import java.util.TimerTask;
import java.util.Date;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public final class TimerUtil {

    // static variable
    private static Log log = LogFactory.getLog(TimerUtil.class);

    // static variable
    private static TimerUtil instance = null;

    // static variable
    private static boolean isCanceled = false;

    // instance variables
    private Timer timer = null;

    // private constructor will prevent any instatiation
    private TimerUtil() {
        log.debug("TimerUtil is instantiated.");
        timer = new Timer();
    }

    private void reloadTimer() {
        log.info("Reload Timer in TimerUtil.");
        if (!isCanceled) {
            timer.cancel(); // Cancel the errored timer
            timer = new Timer();
        }
    }

    /**
     * This static method is used to get the Singleton instance of TimerUtil
     * @return the singleton instance of TimerUtil
     */
    public static synchronized TimerUtil getInstance() {
        if (instance == null) {
            instance = new TimerUtil();
        }
        return instance;
    }

    public void cancel() {
        isCanceled = true;
        timer.cancel();
    }

    public void schedule(TimerTask task, Date firstTime, long period) {
        if (!isCanceled) {
            try {
                timer.schedule(task, firstTime, period);
            } catch (IllegalStateException ex) {
                log.error("Cannot schedule task!", ex);
                reloadTimer();
            }
        }
    }

    public void schedule(TimerTask task, Date time) {
        if (!isCanceled) {
            try {
                timer.schedule(task, time);
            } catch (IllegalStateException ex) {
                log.error("Cannot schedule task!", ex);
                reloadTimer();
            }
        }
    }

    public void schedule(TimerTask task, long delay) {
        if (!isCanceled) {
            try {
                timer.schedule(task, delay);
            } catch (IllegalStateException ex) {
                log.error("Cannot schedule task!", ex);
                reloadTimer();
            }
        }
    }

    public void schedule(TimerTask task, long delay, long period) {
        if (!isCanceled) {
            try {
                timer.schedule(task, delay, period);
            } catch (IllegalStateException ex) {
                log.error("Cannot schedule task!", ex);
                reloadTimer();
            }
        }
    }

    public void scheduleAtFixedRate(TimerTask task, Date firstTime, long period) {
        if (!isCanceled) {
            try {
                timer.schedule(task, firstTime, period);
            } catch (IllegalStateException ex) {
                log.error("Cannot schedule task!", ex);
                reloadTimer();
            }
        }
    }

    public void scheduleAtFixedRate(TimerTask task, long delay, long period) {
        if (!isCanceled) {
            try {
                timer.schedule(task, delay, period);
            } catch (IllegalStateException ex) {
                log.error("Cannot schedule task!", ex);
                reloadTimer();
            }
        }
    }
}
